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Thermodynamics of two, two-dimensional phases formed by CO/sub 2/ chemisorption on MgO

Journal Article · · J. Phys. Chem.; (United States)
DOI:https://doi.org/10.1021/j100297a022· OSTI ID:6036892
Variations in concentrations of CO/sub 2/ adsorbed on MgO with temperature at constant pressure and with pressure at constant temperature at 880 to 950 K indicate a miscibility gap. In the low coverage region the enthalpy of chemisorption is -207 +/- 2 kJ/mol of CO/sub 2/ and the entropy of adsorption is -183 +/- 10 J/(mol deg). The molar enthalpy and entropy transition from the low to high coverage phase are -9 +/- 5 kJ and -13 +/- 10 J/deg. The enthalpies and entropies of adsorption show that the CO/sub 2/ is much more strongly held as CO/sub 3//sup 2 -/ ions on the MgO surface than in MgCO/sub 3/. The number of Mg/sup 2 +/ ions bound to each surface CO/sub 3//sup 2 -/ ion on MgO at 600 to 1000 K must be higher than reported from infrared measurements of CO/sub 2/ adsorbed as CO/sub 3//sup 2 -/ on MgO near room temperature.
Research Organization:
Lawrence Berkeley Lab., CA
DOE Contract Number:
AC03-76SF00098
OSTI ID:
6036892
Journal Information:
J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:13; ISSN JPCHA
Country of Publication:
United States
Language:
English